Lab techniques

Concentration of total drugs and metabolites

The basic requirement for a research laboratory in clinical pharmacokinetics is the availability of sensitive, specific and reproducible analytical methods for the measurement of total or unbound concentration of drugs and their major metabolites. Every assay, either chromatography or immunoassay based, must be validated according to the guidelines set forth by the FDA and preferably published in a peer reviewed journal. The requirement is so fundamental that a clinical study performed using non-validated assays is usually not publishable in a reputable journal. Because of this requirement, my lab devotes considerable effort to the development and validation of analytical methods using HPLC-UV and LC-MS/MS. The following assays are now available in the laboratory, all of which have been validated according to the FDA “Guidance for Industry:Bioanalytical Method Validation” and were published as manuscript or conference abstract:

To explain many observations originated from clinical PKPD studies, one has to utilize various techniques commonly used in the basic biomedical science or the preclinical stages of drug development. Among these techniques employed in my laboratory are the followings: • Characterization of metabolic capacity of human liver microsomes in metabolizing CYP or UGT substrates. • Western blot and rtPCR. • Pharmacokinetics and drug-drug interaction studies in Sprague Dawley rat. • Isolation and fractionation of lipoproteins from plasma to access plasma distribution of drugs among lipoprotein fractions. • Plasma protein studies of new drugs and binding of drugs to different blood cells (i.e. red blood cells and lymphocytes). • Transwell assay using MDCK cell lines transfected with human MDR1 (ABCB1) or MRP2 (ABCC2) genes. This assay is employed to characterize the drug-drug interaction at transporter level. • Caco-2 transwell assay • HepG2 culture to evaluate the effect of diabetes